Lead or like metal sheathed electric cable



0:.22, 1929. .L L' PACI-R f 1,732,984

' LEAD cmy Lm: usuL-snsugisn ELECTRIC CABLE l med aus. 4. wasv zsheets-sheet 1 0t. 22, 1929. .M PACKER 1,132,984

LEAD OR LIKE METAL SHEATHED ELECTRIC CABLE 4:filed Aug, 4, 1925 2Sheets-Sheet 2 Las;

'Raiefed oct. 2'2, i929 UNITED STATES! PATENT ori-ica JOHN LEWIS PACKER,F HUYTON, ENGLAND, 'ASSIGNOR T0 :BRITISH INSULATED CABLES LIMITED, orPREsCoT, ENGLANmA LIMITED L ENGLAND LEAD onr LIIzE METAL SHEATHEDELECTRIC CABLE Appiicationniea August 4, 1925, seriai No. 48,138, and inGreat Britain November zo, 1924.

This invention has reference to electric cables, but primarily to leador like metal covered Ior sheathed electric cables; and it relates moreparticularly to such cables, which when laid, are subject toelectrolytic actions due to electric earth currents or chemical or othercorrosive actions, and in which a covering or coverings of a compound ormaterial such as a bituminous compound or material, red lead, or'thelike, is em-` ployed fory protecting the lead or like inetal sheathagainst such actions, suchcovering or coverings beingv enclosed withwrappings or windings of textile tapepr the like, impregnated withbituminous and other waterproof or water resistant compositions. or 'redlead,

or the like; in some cases such cables are armoured with ordinary steelor like wires or tapes.

It is found in practice that the layers or coverings of bituminouscomposition, red lead, or the like, which lie between the fibroustapings or wrappings, if of a-substantial thicknesswhich is practicallynecessary to achieve the end desired or .very desiroussoften by the heatgiven olf by the cable when under work, and consequently in la'leadsheathed cable, thev lead sheath becomes gradually eccentric to theprotective cover- ,ings owing to its weight or gravity, and thereforethe protective material becomes displaced, and it ceases to a largeextent or wholly, to afford the protection that it otherwise would have,and is necessary; and this happens more readily when the thickness ofmaterial between the fibrous layers or wrappings is increased. l

One of the chief objects and effects of this 'invention is to enable arelatively thick covering or coverings to be used, without the liabilityof de-centralization of the cable proper in relation to its protectivecoverings and thereby reliably protect the cable or lead sheathingagainst electrolytic action,- or other corrosive actions, which asstated, such cables as heretofore made are subi ect to.

The above ends are accomplished under this invention by furnishingoutsidelthe lead `orlike sheathed cable, or the armouring, a covering orcoverings consisting of waterproof and insulating material of relativelyf great tliickness-Lwhich'will be covered with IABILITY COMPANY 0Ematerial to cables) will be centrally held in the cable, and itsconcentricity cannot be upset. In most cases the distance pieces ordevices are of insulating material or non-metallic, so'that the wholeprotective covering is of insulating material, and electrolytic cur- ,l

rents in the earth in which cable is laid caiinot pass through the thickcovering, and so cannot pass to or reach the lead like metal sheath ofthe cable, or armouring when it is enclosed within such a covering; norcan most chemical or corrosive media damage or destroy this covering,and reach or act upon any of the parts of the cable within this thickprotective covering or coverings and they being maintained trulyconcentric, and of even thickness, as describedj under allcircu'rnstances, the cable remains under work continuously protectedagainst all the above detrimental activities. In some cases whereelectric cables lare subject to the actionv of corrosive fluids orsubstances which destroy or deteriorate bituminous compounds ormaterials, red lead is used as the thick protective covering, with thedistance devices; in which case the cable would notbe protected againstthe `deteriorative' effects of electrolytic currents. 'i

In some cases the-thick coverings described are applied in one or morelayers; .and one or more of such coverings may be applied out. side thelead or like sheathing or tapings Or, again, one or more of thecoverings mayv be used outside the armouring of an armoured cable; orthe covering or coverings may be lead sheathing, and also outside thearmourmeans-or device consists of one or more win/dings of helical formof suitable insulating material .which are wound upon the tape Windingsor wrappings in a short pitch helix, as in a spring; and in such a case,the waterproof material of relatively great thickness, will be appliedto the cable in the course of its manufacture, after the helicaldistance means has been applied. Namely, the helical spaces be tweenconvolutions of the helical distance coil or coils, are filled with thematerial and A levelled off in usual way; 4and then the next tapings orwrappings wound on. These may be repeated in a plurality of annularconcentric layers.

Many attempts have been made to carry out this ideal in practice, butonly with partial success, by laying the cables on the so-called solidsystem.. The diflic-ulties of obtaining an entirely As atisfactoryinstallation have proved insuperable, and the use of the solid systemwith lead sheathed cables has fallen into disfavour, and has been almostentirely discarded in favour of cables which are protected with compoundtapes (or jute) and with layers of compound'.

When cables with fibrous impregnated wrappings or tapings are laid inthe ground,

they suffer damage by the dampness, owing to the fact that the tapes,orjute or like windings, for keeping the layers of the waterproofmaterial in position, cannot be sufliciently saturated or impregnatedwith bituminous or other waterproofing or preservative mixture; and inconsequence, they, absorb water, or

' acid or alkaline solutions, which have access to them, and so suchcorrosive or chemical substances get access tothe protective coverings,armouring wires, and to the lead, which in bad conditions results in thecoverings being destroyed or penetrated, and the harmful effect of theexternal activities above specied, on the lead sheathing are free tofollow, v

When 'ute or like material of which the tape windhi'gs 'or wrappings aremade is Wet, it forms a conductor to electrolytic earth cur- 'rents, butby the employmentof the relative;

lv thick insulation Waterproof coverings prouced as describechnamely, bythe distance devicesvand the thick insulated compound or material in theinterspa'ces of same, which lies within the windings or wrappings, thesecurrents cannot pass to or reach the lead or like sheathing at all, orthe metal armouring wires or tapes which are in'some cases ennclosed bysuch=a thick covering; so that by the invention, electrolytic currents,and mo'st chemical and corrosive substances are prevented from actingharmfully on the cable.4 i

vWith regard to the distance devices or means, an advantageousinsulating material which can be used for this consists of a relativelyhard rubber cord or wire, preferably rubber such as is used in the treadot tyres for self propelled vehicles, which besides being aninsulator initself, is not melted or detrimeutally aHected by the pouring orapplying e of the boiling or hot compound or material o r preservativeor protective compound or string or cord saturated with an' insulating"vcompound may in some cases be employed.

Or again, the distance means or devices may be of metal wire, saygalvanized metal or steel wire, the surfaces of which have been providedor covered with a suitable bituminous compound or the like prior tovapplying it to the cable, so that it will make-a firm union with thecovering compound which is applied or filled into the spaces between themetal convolutions or parts,and with the saturated fibrous tapes or wrapings, which are Wound round the .outside o or the outside and inside ofthesethick protective coverings.

lll/*ith regard to the thickness of the said protective coverings, thisnaturally will vary under different circumstances, nameiy, the nature ofthe ground in which the cable is laid, and the degree of danger ordeteriorative Iactivities to which it may be subjected when in theground, but in`an average case the thickness may be from 116th to 1/8thof an inch.

The compound or material used in these coverings should be one that isplastic or pliable at atmospherictemperature, so that it does not crackwhenthe cable is bent during laying or otherwise.`

A cable of the character above described is illustrated in theaccompanying drawings, in which Figure l is a longitudinal elevationwith .parts removed, showing one modification, and Figure 2 is a crosssection of same.

Figures 3 and 4 and 5 and 6 are longitudinal elevations andcrosssections, respectively,

showing twor further modifications of cables according to the invention.

ble; 2 are'wrappings or windings of a plurality of tapes or ribbons oftextile material impregnated with bituminous or other waterproof orWater resistant composition, red lead, or the like; 3 are thedis'tancedevices or means, which 'in the cases shown consist of helically woundcords or wires; 4 is the bituminous or other coveringof insulatingcompound or material of the character above described, or red leadconstituting with the distance devices the relatively thick covering.

In the construction of cable shown in Figures 14 and 2, the insulatingcompound or other material 4 and distance devices 3, are applieddirectly to the outside ofthe lead or like metal sheath l of the cable;and outside this thick covering 3, 4,.are windings or Wrapc ing arewrappings pings 2 bons impregnated with bituminous or other suitablepreservative waterjresistant composition. i

In the modification shownin Figures 3 and 4, next the lead is a coveringof armouring metal wires 5 of any known suitable kind, or.

, the thick coveringI of the insulating comd windings 2y `pound 4, ormaterial as speciied'and distance devices 3; then on these are'furtherwindings orwrappings of saturated textile tape 2'; and upon this isapplied the metal armouring 5, outside which further windings `2X ofsaturated textile ,tapes are applied; and vagain round this is anotherthick covering of insulating compound 4 and distance 'devices 3',outside which further wrappin'gsor f v of `saturated ltextile tapes areapplied. v Y i s regards 'theselvarious coverings and parts forming thecable, these may bevaried in making the cable according to theconditions under which the `cable .isf to work; and the number andthicknesses of the dierent coverings or parts may also similarly bevaried. v

Inthe drawings, the form of the distance piepes is a plurality ofhelically wound cords `or wires3 of relatively short pitch, in therelatively (wide helical spaces betweenl the convolutions of which isiilled the bituminous or other insulating waterproof compound, ormaterial as specified.

The distance pieces 3, over which the textile orlike windings 2 areapplied asy described, and by which such windings and the compound ormaterial 4 are supported and of a plurality of textile tapes or rib-`held concentrically in the cable, ma take diierent forms, but thoseabove descrl ed 1n connection with drawings are advantageous,

being simple and quickly and easily applied Y in manufacture.

As above stated when the devices 3 are of metal wire, say galvanizediron or steel, their surface,prior toapplication, should be covered witha sultable bituminous 0r like comi pound, so that when the coveringcompound 4 is, applied to the cable, it will make a complete and firmunion with thevwires. What is claimed is 1. In an electric cable havingan inner insulated conductor part surrounded by metal, aprotective'coveringadapted to protect saidt metal against electrolyticaction and chemical or other corrosive action, comprising a Waterproofinsulating material having within itdistance devices, such material anddise` tance devices being enclosed within wrappings of textile materialimpregnated with preserving material, andthe'said distance de `;v1cesbeing adapted to support the wrappings and maintain the concentricityand constant thickness of such waterproof insulating material inrelation to the said surroundving metal.

"2. An electric cable comprising a central portion containing theconductor or conduc- A tors, a lead sheathing enclosing same, arelatively thick covering of insulating waterproof material havingwithin it distance devices and wrappings 'of textile material outsidesaid covering, said distance devices being adapted to support saidwrappings.

3. An electric cable comprising a central portion containing aninsulated conductor, metal armor-around said central portion, arelatively thick covering of waterproof insulation material around saidarmor having within it distance devices, wrappings of texytile materialimpregnated with preserving material, enclosing the said waterproofmaterial, said distance devices supporting the wrappings concentricallyto the conductor portion of the cable.

4. An electric cable comprising a central Q portion containing a sheathoutside same, the metal sheath, wrappings of vvtextile materialimpregnated with preserving outside said armoring, a thick coveringJaround said armoring consisting of insulating waterproof material,having within it a distance piece, and wrappings of textile materialimpregnated with preserving material surrounding said latter covering,and supported concentrically by the distance devices thereof. Y

5. An electric cable-comprising an inner conductor, a soft metal partcontaining the conductor or conductors,

a covering adapted -to protect metal parts of the cable againstelectrolytic action andv `chemical or other corrosive action,comprisvmetal armoring outside dmaterial within it d1stance devicesadapted to maintain the concentricity and constant thickness of suchwaterproof insulatin material ir relation to the parts ofthe cab eenclosed withinit, wrappings of textile material round saidcovering,lmetal armouring, and outside said armouring a relatively thickcovering of insulation Waterproof material having Within Ait distancedevices and Wrappings of textile material round the latter ported by thesaid distance devices.

In testimony whereof I have signed my name to this Specification.

JOHN LEWIS PACKER.

` ing a` waterproof insulation material having thlck covering sup-

